text: As stormwater regulations become increasingly stringent, many states and municipalities have developed criteria to govern the use and sizing of HDS systems, and publish lists that identify acceptable HDS systems. Other jurisdictions evaluate the applicability of HDS on a site-specific basis. It is increasingly common to use HDS as the first component of a treatment train, a combination of BMPs in series, to remove coarse solids and floatable pollutants that can rapidly clog other BMPs thus prolonging their maintenance cycle.